TAOISEACH Leo Varadkar has said a coalition between Fine Gael and Sinn Féin is "not an option" and compared such an outcome to a "forced marriage".
Meanwhile, Mr Varadkar said that it may take months to form a government given the likely result that will see three parties with roughly the same Dáil numbers.
Mr Varadkar said Fine Gael's position on ruling out a government deal with Sinn Féin hasn't changed since the election and his party won votes on that basis.
He said: "It wasn't a tactic or a strategy. It's what we honestly believe and for us coalition with Sinn Féin is not an option
"We're willing to talk to other parties about the the possibility of forming a government, one that can lead the country forward for the next five years."
He responded to Sinn Féin leader Mary Lou McDonald's argument that it is "fundamentally undemocratic" for Fine Gael and Fianna Fáil to exclude her party.
Mr Varadkar congratulated Ms McDonald's party on its results but he said: "Bear in mind we have three parties that got roughly the same share of the vote and the same number of seats and we all have a mandate and everyone's mandate needs to be respected."
He added: "Nobody can be forced into some sort of forced marriage or forced coalition.
"In order to form a government together you have to have roughly the same views around the courts and the criminal justice system, around how the economy and society should be run, and also how democracy should function.
"That's what makes my party, Fine Gael, not compatible with Sinn Féin."
Mr Varadkar was asked about Fianna Fáil leader Micheál Martin's apparent softening of his party's stance towards Sinn Féin.
He said Mr Martin's comments are "open to interpretation" on what he believes the next step should be.
"I think we need to count the votes and see what the lie of the land is in the next day or two and work on things from there," the Taosieach said.
Asked about his offer of a grand coalition with Fianna Fáil, Mr Varadkar said:
"Any of those discussions would have to happen between the leaders and the key people in the parties and not across the media."
Mr Varadkar said he wasn't concerned that Ms McDonald has made contact with left-wing parties in relation to forming a possible government.
He said: "She hasn't been in touch with me yet but we would talk on occasion.
"I understand what she's said is she's going to seek to form a coalition of the left-wing parties which doesn't include Fianna Fáil or Fine Gael.
"I'm not sure if that's possible on the numbers. I think it's going to be a number of weeks or a number of months before we're in a position to form a government."
Asked if he will be picking up the phone to her, he said: "No. Not at this stage anyway."
Sinn Féin's Paul Donnelly topped the poll in Mr Varadkar's Dublin West constituency and was elected on the first count.
Mr Varadkar will be re-elected but will have to wait for a later count.
Earlier, Fianna Fáil leader Micheál Martin said he is no longer ruling out forming a government with Sinn Féin.
In a very clear change of stance since voters went to the polls, he now claims he will tease out the election results and policy difference “with all concerned” in the coming days.
“I think we’ll let things calm down today. We’ll assess it when the full count is in, and the full number of seats is in. I’m a democrat. I listen to the people. I respect the decision of the people,” he said.
The Cork TD, who has now led Fianna Fáil into three elections, warned there remains "significant incompatibility" between his party and Sinn Fein on key policy issues.
When asked he still could not go into coalition with Sinn Féin on moral grounds, Mr Martin replied: "Today is not the day for… I’ve heard the people speak today. The people have voted in number and I respect that.
"For any government to sustain there has to be compatibility in the political programme for that government.
"Also, you know, one’s polices and one’s positions and principles don’t change overnight. There are significant issues there.
"But as I say over the next number of days we’ll tease those out with all concerned."
Speaking at the Nemo Rangers GAA count centre in Cork, Mr Martin predicted that Irish politics has become far more fragmented and volatile.
Meanwhile, Green Party leader Eamon Ryan has been elected on the first count in Dublin Bay South, and has said he is willing to listen to Sinn Fein and other parties about forming a coalition government.
Ryan topped the poll in his constituency with a share of 8,888 first preference votes. The quota was 7,919.
He said he was thrilled with the win and hoped the party would get at least nine more seats, making it an option to help form a government.
"It’s a relief, we had a really good team. We had a really good campaign. We knocked on every door in three and a half weeks. That takes some doing and we had great help.
"Now my focus is on the rest of the country. Every other candidate in the party is part of a wider team. I am glad we have one seat in the bag and hopefully there will be more."
He confirmed he had been in contact with Sinn Féin leader Mary Lou McDonald earlier in the day.
“She rang me earlier on. I missed the call and rang her back. She missed my call but I think we have to sit down together first.
“I do think that [idea Labour Leader] Brendan Howlin was saying the other day is what I have been saying – that Labour, ourselves and the Soc Dems and a few Independents that we might be naturally close to, we should see if that block is there and if there is negotiating power in it.
“Come what may, I am hoping we can get a team up to double figures and we will do what we can in the national interest in whatever way we can.”
Sinn Féin’s Chris Andrews, came second in the poll and looks set to take a seat for the party in Dublin Bay .South at the expense of sitting TD Kate O’Connell.
Fine Gael’s Eoghan Murphy was third in the poll with 6,346 first preference votes. Fianna Fail’s justice spokesperson Jim O’Callaghan looks set to take the final fourth seat. He totalled 5,474 votes.
O’Connell was fifth with 4,624 first preferences as counting continues.
Ms McDonald said she has already spoken to representatives of the Green Party, Social Democrats and People Before Profit.
"I said throughout the campaign and I meant it that we need change, that we need a new government," she said.
"The best outcome is with a government without Fianna Fail or Fine Gael so that's the first thing I want to test, whether or not that's possible.
"I also have consistently said that I will talk to and listen to everybody. I think that's what grown-ups do. I think that's what democracy demands.
"I am advised I should have had a running mate in my own consistency, that's for sure.
"We certainly could have fielded another candidate, but hindsight is a great thing. I'm just delighted that the candidates that we did run have performed so astonishingly well and have come back so strongly."
However, she said that it is not a sustainable position for Taoiseach Leo Varadkar and Mr Martin to say that they will not speak to Sinn Féin after the party received such a sizeable vote.
"This is not a protest vote. This is certainly an election that is historic in proportions, this is changing the shape and mould of Irish politics.
"This is not a transient thing - this is just the beginning," she said.
Ms McDonald said the support for Sinn Fein is a "big statement of change".
"It's a big statement that this is no longer a two-party system, it's a statement that people want a different type of government and people have great confidence in us, and I say that with all humility.
"My first port of call is the other parties to see whether or not can we actually give a new government, a government without Fianna Fail or Fine Gael. That's item number one.
"Beyond that of course I will talk to and listen to everybody with the express intent of getting a programme for government that delivers for people.
"We are not doing another five years of housing crisis, that is not on the agenda. We are not going to simply allow record (hospital) trolley counts, day in, day out, week in, week out.
"We want families and workers to have breathing space, I mean financial, economic security and breathing space.
"Those are the items on the agenda, I will talk to everybody about those things."
Social Democrats TD Róisín Shortall said she has not spoken to Sinn Féin leader Mary Lou McDonald yet today.
She added that the party will be speaking to "all parties."
"Today we are concentrating on just our own numbers and hoping that we will maximise the number of TDs," Ms Shortall said.
"Then we will look around see what the lay of the land is in relation to other parties, but we have not vetoed any party, and we are very clear about that throughout the campaign. We are happy to talk to all parties."
She said it was "far too early" to say whether the Social Democrats would consider going into government with Sinn Féin, adding that "it depends on what the numbers are."
On her own party’s performance, she said it is in a "serious contention in three constituencies as well as Catherine and myself so I am very happy with the performance."
With regards her own first preference vote, which is down by around 4,000 votes, she said she knew there was a "tidal wave" coming, "in the context of that I was happy to get 19pc of the vote."
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